Sunitinib is chemically described as N-[2-(diethylamino)ethyl]-5-[(Z)-(5-fluoro-1,2-dihydro-2-oxo-3H-indol-3-ylidine)methyl]-2,4-dimethyl-1H-pyrrole-3-carboxamide as represented by Formula I.

Sunitinib is an oral multi-kinase inhibitor and useful for the treatment of gastrointestinal stromal tumor and advanced renal cell carcinoma. Sunitinib is commercially available as the L-malate salt, which is described chemically as butanedioic acid, hydroxy-, (2S)—, compound with N-[2-(diethylamino)ethyl]-5-[(Z)-(5-fluoro-1,2-dihydro-2-oxo-3H-indol-3-ylidine)methyl]-2,4-dimethyl-1H-pyrrole-3-carboxamide (1:1).
U.S. Patent Application Nos. 2003/0069298 and 2007/0191458 describe the preparation of crystalline Forms I and II of L-malic acid salt of sunitinib. According to these applications, crystalline Form I of L-malic acid salt of sunitinib is prepared by slurrying a poorly crystalline or crystalline Form II of L-malic acid salt of sunitinib in acetonitrile. Crystalline Form II of the L-malic acid salt of sunitinib is prepared by dissolving crystal Form I of L-malic acid salt of sunitinib in tetrahydrofuran and water and allowing the solvent to evaporate overnight.
WO 2009/067686 describes processes for preparing crystalline Forms of racemic sunitinib malate, sunitinib hemi-L-malate and compositions containing sunitinib base and L- or racemic malic acid.
WO 2009/104021 describes processes for preparing crystalline Forms III and IV of sunitinib L-malate.
WO 2009/104021 describes that Form II of sunitinib L-malate is hygroscopic, thermodynamically unstable and appears to readily convert to Form I.